Our LD-FPI-BB15 leak detection sensor combines brass and a Buna float designed for oil or fuel based liquids. With its extra weight and slim outside diameter of 1 ½”, this sensor is ideal for deep, tight tanks/spaces. <OR> The sensor’s extra weight pushes it to the bottom of the deepest tanks. The sensor’s 1 ½” in outside diameter also allows for it to fit into tight spaces.